Method for improving calcium carbonate scale inhibitor efficiency

Abstract

This technology relates to a system and method of delaying CaCO3 scale formation in an oil production well using a phosphonate scale inhibitor and a chelating agent. The addition of a small concentration (less than 5 ppm) of a chelating agent to the phosphonate scale inhibitor delays the scale induction time and scaling time of CaCO3 scale.

What is claimed is: 
     
         1 . A method of delaying a calcium carbonate (CaCO 3 ) scale formation comprising:
 adding a phosphonate scale inhibitor to a synthetic produced water;   adding a chelating agent to the phosphonate scale inhibitor in the synthetic produced water, wherein the chelating agent comprises a polyamino-polycarboxylic ligand selected from nitrilo triacetic acid (NTA), hydroxyethylimino diacetic acid (HEIDA), ethylenediamine tetraacetic acid (EDTA), hydroxyethyl ethylenediamine triacetic acid (HEDTA), diethylenetriamine pentaacetic acid (DTPA), and hydroxyethyl ethylenediamine triacetic acid (HEDTA);   flowing the synthetic produced water through a capillary tube in an oven at a user defined temperature and a user defined pressure;   measuring a pressure difference (ΔP) as a function of time during the flow of the synthetic produced water through the capillary tube in the oven; and   determining a scale induction time and a scaling time from the ΔP, wherein adding the chelating agent to the phosphonate scale inhibitor delays the scale induction time and the scaling time.   
     
     
         2 . The method of  claim 1 , wherein the phosphonate scale inhibitor comprises amino trimethylene phosphonate (ATMP), bishexamethylene triamine pentamethylene phosphonate (BHPMP), hexamethylenediamine tetramethylene phosphonate (HDTMP), diethylenetriamine pentamethylene phosphonate (DETPMP), ethylene diamine tetramethylene phosphonate (EDTMP), 1-hydroxyethylidene-1,1-diphosphonate (HEDP), polyamino polyether methylene phosphonate (PAPEMP), 2-phosphonobutane-1,2,4-tricarboxylic acid (PBTC), or phosphate esters. 
     
     
         3 . The method of  claim 1 , wherein a concentration of the chelating agent added to the phosphonate scale inhibitor is less than 5 ppm. 
     
     
         4 . The method of  claim 3 , wherein the chelating agent comprises hydroxyethyl ethylenediamine triacetic acid (HEDTA). 
     
     
         5 . The method of  claim 1 , wherein the scale induction time and scaling time is delayed by 1.3 to 10 times as compared to a method that does not include the chelating agent. 
     
     
         6 . The method of  claim 1 , wherein the user defined temperature is between 25-250° C. 
     
     
         7 . The method of  claim 1 , wherein the user defined pressure is between 0.34-20.7 MPa. 
     
     
         8 . The method of  claim 1 , further comprising determining the scale induction time when measuring an increase in the ΔP from a baseline value of negligible ΔP. 
     
     
         9 . The method of  claim 1 , further comprising determining the scaling time when measuring the ΔP of 6.89×10 −3  MPa. 
     
     
         10 . An integrated system to measure a delay in calcium carbonate (CaCO 3 ) scale formation comprising:
 a pump system to pump a mixture of synthetic brines, the pump system comprising:
 a first pump comprising a synthetic cation brine; 
 a second pump placed parallel to the first pump, comprising a synthetic anon brine; and 
 a third pump placed parallel to the second pump and the first pump, comprising the synthetic anion brine, wherein the synthetic anion brine comprises a phosphonate scale inhibitor and a chelating agent; 
   an oven, set at a user defined temperature;   a pre-heating coil placed inside the oven, which is configured to receive the mixture of synthetic brines from the pump system;   a mixing chamber placed downstream of the pre-heating coil inside the oven, which is configured to receive the mixture of synthetic brines from the pre-heating coil;   a capillary coiled tube placed downstream of the mixing chamber in the oven, which is configured to receive the mixture of synthetic brines from the mixing chamber; and   a back-pressure system, set at a user defined pressure.   
     
     
         11 . The integrated system of  claim 10 , wherein a pressure difference is measured across the capillary coiled tube as a function of time. 
     
     
         12 . The integrated system of  claim 11 , wherein a delay in the increase of the pressure difference is indication of a scaling induction time, which further indicates delay in CaCO 3  scale formation. 
     
     
         13 . The integrated system of  claim 12 , wherein the pressure difference of 6.89×10 −3  MPa indicates a scaling time. 
     
     
         14 . The integrated system of  claim 10 , wherein the scale inhibitor in the third pump comprises amino trimethylene phosphonate (ATMP), bishexamethylene triamine pentamethylene phosphonate (BHPMP), hexamethylenediamine tetramethylene phosphonate (HDTMP), diethylenetriamine pentamethylene phosphonate (DETPMP), ethylene diamine tetramethylene phosphonate (EDTMP), 1-hydroxyethylidene-1,1-diphosphonate (HEDP), polyamino polyether methylene phosphonate (PAPEMP), 2-phosphonobutane-1,2,4-tricarboxylic acid (PBTC), or phosphate esters. 
     
     
         15 . The integrated system of  claim 10 , wherein the chelating agent in the third pump comprises hydroxyethyl ethylenediamine triacetic acid (HEDTA). 
     
     
         16 . The integrated system of  claim 15 , wherein the concentration of the chelating agent is between 0.1-8 ppm. 
     
     
         17 . A method to delay calcium carbonate (CaCO 3 ) scale formation in an oil production well comprising:
 adding an additive comprising a chelating agent to a scale inhibitor in a produced water stream from the oil production well.   
     
     
         18 . The method of  claim 17 , wherein the chelating agent comprises a polyamino-polycarboxylic ligand selected from nitrilo triacetic acid (NTA), hydroxyethylimino diacetic acid (HEIDA), ethylenediamine tetraacetic acid (EDTA), hydroxyethyl ethylenediamine triacetic acid (HEDTA), diethylenetriamine pentaacetic acid (DTPA), and hydroxyethyl ethylenediamine triacetic acid (HEDTA). 
     
     
         19 . The method of  claim 17 , wherein the additive comprises less than 5 ppm of the chelating agent. 
     
     
         20 . The method of  claim 17 , wherein the scale inhibitor comprises amino trimethylene phosphonate (ATMP), bishexamethylene triamine pentamethylene phosphonate (BHPMP), hexamethylenediamine tetramethylene phosphonate (HDTMP), diethylenetriamine pentamethylene phosphonate (DETPMP), ethylene diamine tetramethylene phosphonate (EDTMP), 1-hydroxyethylidene-1,1-diphosphonate (HEDP), polyamino polyether methylene phosphonate (PAPEMP), 2-phosphonobutane-1,2,4-tricarboxylic acid (PBTC), or phosphate esters.